---
title: "How long does phentermine take to work?"
description: "Phentermine may curb appetite on day 1, but weight change is tracked over weeks and varies with diet, activity, sleep, and side, with clinician guidance."
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last-updated: 2026-08-22
---

# How long does phentermine take to work?

> Phentermine may curb appetite on day 1, but weight change is tracked over weeks and varies with diet, activity, sleep, and side, with clinician guidance.

---

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